Possible with VBA to change the numbers to negative as you enter them.
Private Sub Worksheet_Change(ByVal Target As Range)
Const myRange As String = "A1:A10"
On Error GoTo endit
Application.EnableEvents = False
If Not Intersect(Target, Me.Range(myRange)) Is Nothing Then
With Target
If Application.IsNumber(.Value) And _
Left(.Value, 1) <> "-" Then
.Value = .Value * -1
End If
End With
End If
endit:
Application.EnableEvents = True
End Sub
This is sheet event code. Right-click on sheet tab and "View Code".
Copy/paste the above into that sheet module.
Edit myRange to suit. Alt + q to return to the Excel window.
Gord Dibben MS Excel MVP